Spark-plug.



H. M. HOWARD c@ J. A. MCHARDY. SPARK PLUG. AFPucATloH min ma. ls. |913.

UNITED sTaTns e HAROLD M. HOWARD AND JAMES A. 'MCHLARDY, OF YBOVDENEE, RHTDE STLQl,

SPARKELUG.

Application ,led January 13, 1913.

Be it known that We, HAROLD M. HOWARD and Jamas n.. MCHAnm, citizens ot' the lnited States, and residents of the city of lrovidenee, in the eount'jy of AProvidence and State of Rhode Island, have invented certain new and useful Improvements in Spark-Plugs, of which the following is specification.

This invention relates to spark plugs, and has for its object to provide a plug of this char.. eter having` abody `shell rompletely closed at its inner end to prevent carbon or oil from getting into the, shell and short eireuiting the electrodes.

A further object of theinvention is to support the central electrode in the insulat ing material, which closes the shell and to extend this electrode beyond the inner end of the shell and to make the second electrode in the form of a loop to extend from one side of the shell to the other, around the end of said central electrode, whereby by supporting both ends of this second electrode it is prevented from warping to better eontroi the width of the sparking gap.

A further object of the invention is to form the inclosed insulating material in two parts, the inner part serving' to close the oorresponding portion ofthe shell and is itself held in position by the outer insulating portion., a packing being provided between the two portions to serve as a cushion and prevent breakage.

A still further object of the invention is to reduce the inner extremity of the central electrode where it passes through the end porcelain. so as to minimize the transmission ot' heat therethrough to the inner porcelain insulation to reduce the liability of breakage. l

lVith these and other objects in fieiv, the invention consists of certain novel features of construction, as will be more fullyl described and particularly pointed out in the appended claims.

Of the accompanying drawings: Figure 1- is a sectional elevation or" my improved spark plug. Fig. '2-- is an enlarged view showing the means for regulating the length of the central electrode to control the Width of the sparking gap.

Referring to the drawings, 10 designates the outer end of the cylinder of an internal combustion engine to Which our improved spark plug is shown as being attached. ln

Serial No. 7.21.5411.

this plug li is the shell or easing ivheh niav be constructed et any suitable eonffiueiin'n material, seh iron, steelj l like, inn tuhul y 'l this shell at l2 the ev int end or' this il porcelain binding et th l is pro! turned ai the end constructed e tei-iai, such as outer fare of th fiush with the f ,1 1 A shell. and its i1U concave as at i. the eorespl mai n insula r 1 n. s suiatina einher :ng the redueeli as at l? to pass throufzh Aa spending' hole :n the end member oi sula'tion. The protruding end oi this eleotrode is threaded and provided with a thimble or sleeve 28 and a cheek mit 2%), wherehv the sleeve may be adjusted longitudinal to regulate the gap across which the spark is to jump to `he `second electrode. 'ihk ond electrode 30 is preferably formed Wire of suitable material. lient into the 'to of loop and having` ends driven e forced into e'orresponlfling holes in the end. oi the shell 'to secure and support the same, @ne advantage of this construction is that by supporting both ends of this electrode tendency to warp out of position is reduced to the i'nii'iimuni, thereby preserving the required gap between the electrodes vshen in operation.

'lfhe shell oti the ordinary spark plug,` left if'acant or open at its eid and an emes ier sive charge ot' rai-bon or oil soon fiils up this Chamber and slime circuits the eleotrodes. rendering' the spark plu;- inoperati ve until removed and cleaned. To obviate this dillieultv Wehave completely closed the 11n shell by positioning the Closing member 17 of the insulation at the inner end thereof the tWo insulating members which serves a-. double purpose, iirst it prevents the two hard surfaces from contacting Withfeach other again .reducing the lliability of break age, and second, it serves to positively prevent any oil or carbon from working up throughthe central electrode hole thereby.

positively preventing 'short circuitin of the electrodes through `the porcelain within the shell. i 1

lVe claima j Y l l. A spark plug comprisingan outer shell having an inturned lip adjacent its inner end, insulating material 4in saidvshell'formed of a relatively short inner member and a relatively long outer member, the inner member resting at its inner end against said e lip and comprising-a block completely lling the corresponding portion of the shell, the outer end of the inner member being concaved and the innerend of the outer member v being correspondingly convened, a ymember :engaging said shell :and clamping the outer insulating member against the inner mem- ;ber, and electrodes projecting from the innerend of the plug to form aspark gap.

2. -A vspark plug having apvbodyj portion closed at its inner end, an electrode p110j,ec'tv ing `beyond the y closed end, av grounded "ellecgJ trode i'ormedof a looped gwire and-'spaced from the end ofthe'projectingfelectrodeto' i' form a spark gap, said projecting electr'c'lefV being provided with a thin'ible adjustable jI toward and from said looped -wire to Yregu 'i 4 late the spark gap, and means vfor' locking said thimble in any adjusted position.

In testimony whereof We'aiiixour signa? tures in presence of two. Witnesses.

HAROLD M. I-Iovviiiu). i.

Witnesses: HOWARD E. BARLoW,

E. I.V OGDEN.

JAMEsjaMCnAiinYi-i.- 

